Sterilizing apparatus, for example for the purification of water, are known in which purification is achieved by means of one or more ultraviolet radiation sources mounted in a large cylinder which are surrounded by cylindrical protecting tubes. The water to be purified is circulated through the large cylinder and between the protecting tubes. This known apparatus, for instance, is disclosed in U.S. Pat. Nos. 3,456,107, 3,462,597, 3,562,520 and 3,566,105, respectively.
It is extremely important that sterilizing apparatus of the type described work in a satisfactory manner, i.e. with sufficient capacity of purification. However, should for some reason this capacity decrease so that the quality of the discharged water cannot be guaranteed, the apparatus must automatically be switched off, so that water in which bacteria killing is unsatisfactory must not be allowed to pass through the unit.
Furthermore, it is very important that the liquid which is to be exposed to ultraviolet light is clear and free from suspended particles, because the transmission ability of the ultraviolet light decreases considerably if the liquid is cloudy. Therefore, the apparatus also comprises a filter having a readily exchangeable filter cartridge through which the liquid passes before reaching the chamber in which it is exposed to ultraviolet light.
Some disadvantages of the apparatus as shown and described in the above U.S. patents are that they are expensive because they include complicated sensor systems for detecting the intensity and the wave length of the ultraviolet light, as well as complicated cleaning systems for the glass in the apparatus which is irradiated by the ultraviolet light, and becomes soiled and dirty because of insufficient cleaning of incoming water or other type of liquid.
This invention relates to a sterilizing apparatus for liquid, preferably water, and having a light source emitting ultraviolet radiation. The light source is arranged to emit radiation through a chamber through which a liquid passes to be sterilized, with the liquid, prior to flowing through the chamber, passing through a filter.
An object of the present invention is to provide a sterilizing apparatus which is controlled by simple components and is safe and reliable in operation, easy to install, and can be manufactured at a price which permits widespread use in countries having water supply problems.